A shielding assembly for an infusion system includes a plurality of compartments and a door for each compartment, and provides a radioactive radiation barrier for the compartments. One of the compartments contains a radioisotope generator of the infusion system and another of the compartments may contain a waste bottle of the infusion system. An opening into each of the generator and waste bottle compartments may be oriented upward, and the opening into the latter may be at a higher elevation than the opening into the former, for example, to facilitate independent removal and replacement of each. A door of at least one of the compartments, other than the generator compartment, when closed, may prevent the door of the generator compartment from being opened. A cabinet structure for the infusion system may enclose the shielding assembly and secure the generator.